Thank you SO much for putting both cables on the same side instead of one on each side. I've always wondered why the suppliers of modern Amiga PSU replacements can't seem to figure this out. Great work!
The forward voltage of a zener diode is like a normal diode, like 0.7 volt. The difference is the reverse voltage. A normal diode will block the current up to a significant voltage. But a zener diode breaks down and suddenly starts conducting at, for example, 15 volt. That voltage is the value of the zener diode. And the change to conducting is very abrupt and precise which make them suitable as voltage reference. You can measure it with the diode in reverse, a 1 k ohm resistor in series and for example a 24 V power supply. Or with a power supply that has a current limiter (use a low current not to destroy the zener diode).
Switching power supplies can be tricky to troubleshoot if you are not very familiar with them. But, when you see no voltage on the secondary you can bet it's not switching. That appears to be a zener diode, it may be possible to find its avalanche voltage if it still works. Lots of failures will cause the power MOSFET to fail too. Many times, it can all originate with a single bad electrolytic capacitor in the switching circuit - it's usually just a very small one.
When I built my A500 power supply, I used that connector off of Ebay, some trailer wiring, the PT-65B, an enclosure from Mouser, and a power cord from a dead power strip. It worked a treat, but my A500 is still dead. At least the power supply works!
I built an Amiga PSU out of a PicoPSU - they can provide some serious wattage and have 5 and 12V wires. Worked great on a 600 crammed with upgrades and I assume 500's and 1200's as well. Just desolder the ATX header and wire up the positives, negatives and ground to the Amiga connector. Just need the PicoPSU, Amiga power connector, 12V DC power supply with adequate wattage and some medium gauge wire. I wrapped the whole setup in silicone tape and it's been working for years now.
So, did you cut off the cable's shielding? That's connected to the outer shielding on the plug, right? Isn't that the same connection as the shield pin? I'm refurbishing an A1200 mb but I don't have a psu, so have an old ATX psu I'm going to use to start with, but I need to buy the right flex cable to connect to the dp-215 (on order) to the ATX, and I've found some 6A 5 core cable.
Thank you SO much for putting both cables on the same side instead of one on each side. I've always wondered why the suppliers of modern Amiga PSU replacements can't seem to figure this out. Great work!
Thanks!
Nice work ! They only thing I would of done was to add heat shrink over the line voltage switch tabs.
Lovely video. It would be funny if you include a jump scare of a fire truck in the video, right after you say “might burn my house down”. 😉
Good one! :)
The forward voltage of a zener diode is like a normal diode, like 0.7 volt. The difference is the reverse voltage. A normal diode will block the current up to a significant voltage. But a zener diode breaks down and suddenly starts conducting at, for example, 15 volt. That voltage is the value of the zener diode. And the change to conducting is very abrupt and precise which make them suitable as voltage reference. You can measure it with the diode in reverse, a 1 k ohm resistor in series and for example a 24 V power supply. Or with a power supply that has a current limiter (use a low current not to destroy the zener diode).
Nicely explained, and extra points for stating the correct test procedure.😉
Thanks for the info :)
It is Arctic Retro Friday again!! 💾🖱️🖥️🔌👍🏻Great Power Supply!
Don't you have better things to do on a friday ?? No, that's great. Thanks!
Switching power supplies can be tricky to troubleshoot if you are not very familiar with them. But, when you see no voltage on the secondary you can bet it's not switching. That appears to be a zener diode, it may be possible to find its avalanche voltage if it still works. Lots of failures will cause the power MOSFET to fail too. Many times, it can all originate with a single bad electrolytic capacitor in the switching circuit - it's usually just a very small one.
OK, thanks for the insight :)
Nicely done!
Thank you! Cheers!
i would google "phihong psm-500 schematic" from the board video at 6:30 time.
Thanks. Can't find anything that looks correct. Do you have a direct link ?
When I built my A500 power supply, I used that connector off of Ebay, some trailer wiring, the PT-65B, an enclosure from Mouser, and a power cord from a dead power strip. It worked a treat, but my A500 is still dead. At least the power supply works!
That's unfortunate :)
I built an Amiga PSU out of a PicoPSU - they can provide some serious wattage and have 5 and 12V wires. Worked great on a 600 crammed with upgrades and I assume 500's and 1200's as well. Just desolder the ATX header and wire up the positives, negatives and ground to the Amiga connector. Just need the PicoPSU, Amiga power connector, 12V DC power supply with adequate wattage and some medium gauge wire. I wrapped the whole setup in silicone tape and it's been working for years now.
Thanks for sharing
Nice case and psu! Well built 🙂
Thanks a lot :)
So good to see there are actually PSU modules that almost fit the old housing. Folks without a 3D printer could maybe also find ways to make it fit.
Thanks :-)
You're welcome! Thanks a lot :)
Great video, what happened to the white switch you were going to use in place of the original? 👍
I did not use it. Save it for later :)
So, did you cut off the cable's shielding? That's connected to the outer shielding on the plug, right? Isn't that the same connection as the shield pin? I'm refurbishing an A1200 mb but I don't have a psu, so have an old ATX psu I'm going to use to start with, but I need to buy the right flex cable to connect to the dp-215 (on order) to the ATX, and I've found some 6A 5 core cable.
A zenerdiode has voltage drops in both directions so it has to be measured differently.
Ok, thanks
Dood do one on the VICMODEM.
Great video :) C=
Thanks! 😊
DOOD!